Welcome to the "Roo Kroo!"
just a caution, i think your Sienna's max tow capacity is 3500lbs. the Roo 17 has a GVWR of 3841lbs., well over your max capacity. even it's fictional "dry" weight is 2872lbs., which doesn't count the weight of "options" such as: oven, awning, a/c, spare tire, grill, battery and so on.
from the factory, my Roo weighed 400lbs. over its "dry" weight and i had the regular "options".
you'll have to be very careful how you load the trailer and make sure you have a good WDH with sway control.